SPIDYAN, a MATLAB library for simulating pulse EPR experiments with arbitrary waveform excitation.

Area of Science:

• Magnetic Resonance Spectroscopy
• Computational Chemistry
• Quantum Dynamics

Background:

• Arbitrary waveform generators (AWGs) create frequency-swept chirp pulses for electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR).
• These pulses achieve inversion over hundreds of MHz, offering defined flip angles and increased sensitivity.
• Sequential excitation of spectral transitions can lead to novel effects in established pulse EPR sequences.

Purpose of the Study:

• To develop a MATLAB library for simulating pulse EPR experiments, particularly ultra-wideband (UWB) EPR.
• To model spin dynamics accurately, accommodating various spin systems and pulse sequences.
• To provide a tool for exploring new effects arising from frequency-swept chirp pulses.

Main Methods:

• Development of the SPin DYnamics ANalysis (SPIDYAN) MATLAB package for simulating spin dynamics.
• Implementation of support for one-spin and two-spin systems with arbitrary spin quantum numbers.
• Inclusion of models for solving the Liouville-von Neumann equation (neglecting relaxation) and the quantum mechanical master equation (including relaxation).
• Integration of a simple RLC circuit model for resonator response and a subroutine for constant adiabaticity factor waveform computation.
• Enhancement of computational efficiency through precomputed propagator lookup tables.

Main Results:

• SPIDYAN can simulate pulse EPR sequences using rectangular and frequency-swept chirp pulses, including phase cycling.
• The software handles various detection operators, including transition-selective ones.
• Simulations of spin-echo and population transfer experiments demonstrate the library's capabilities.
• The tool accounts for resonator bandwidth limitations and can compute waveforms for constant adiabaticity.

Conclusions:

• The SPIDYAN library is a versatile tool for simulating spin dynamics in UWB EPR and other NMR experiments.
• It enables the exploration of novel phenomena arising from frequency-swept chirp pulses.
• The software provides a robust platform for theoretical investigations in magnetic resonance spectroscopy.